Elevators are raised and lowered in guideways using cables which are called ropes. Rollers on the elevators move along the guideways, keeping the elevators centered.
Uneven loads in elevators tend to tip the elevators. Undesirable tipping is controlled by simple or complex mechanisms. Occasionally when riding an unevenly loaded elevator a passenger is aware of sounds related to roller and guideway contact, particularly when starting. The problem of controlling tipping is particularly acute with large room-sized elevators.
Needs exist to maintain elevators level with simple and easy-to-install equipment.